000
FXUS63 KAPX 211121
AFDAPX
Area Forecast Discussion
National Weather Service Gaylord MI
621 AM EST Wed Feb 21 2018
.NEAR TERM...(Today through Tonight)
Issued at 252 AM EST Wed Feb 21 2018
...Drier and colder...
High Impact Weather Potential...Ongoing hydro issues across lower
Michigan.
Pattern Synopsis/Forecast...Surface low pressure continues to
advance up into Ontario/Quebec with attending sharp cold front
trailing southwestward and just about to clear SE lower Michigan
as of 06Z. Strongest mid level deformation/F-gen processes and
ongoing axis of precip trails behind the surface front...running
from Texas...up through the Midwest then crosses central/southern
lower Michigan. Still raining across the SE counties...although
precip axis should finally shift out of those counties around
daybreak. Temperatures have fallen to at or below freezing back
across the rest of the CWA. Trailing shallow moisture and flow off
the lakes has managed to produce some -FZDZ and/or light snow
showers during the overnight hours...especially in the higher
terrain.
Upstream...Strong high pressure is building across the
central/northern plains this morning along with a colder/much
drier airmass that is now edging into the western Great Lakes.
Surface high...cold/dry air will build through the state
today/tonight bringing a quieter stretch of weather.
Primary Forecast Concerns...ongoing areal and river flooding.
Will probably have to keep some PoPs in the forecast very early
on as back edge of post frontal precip axis slips out of the SE
counties AND we get some nuisance shallow lake induced precip in
the snowbelt areas. But incoming strong high pressure/subsidence
and dry air will eventually win out and bring a diminishing trend
to cloud cover as we go through day. Surface temps will continue
to fall off heading into the morning hours. And with continuing
cold advection through the day...don`t expect they will move
upward very much even with increasing sun. Clearing skies heading
into tonight along with diminishing winds will result in a rather
cold night. We may get some increasing mid and high cloud cover
trying to sneak into the southern counties overnight. but single
digit to the teens low temperatures should be easily attainable.
Hydro concerns. Various rivers/streams continue to rise especially
in the SE part of the CWA where highest rainfall amounts have
occurred. River flood warnings will of course remain in effect for
the next few days and there may be a few more added. Ongoing
flood warning for the SE counties expires at 1415Z this morning
which is probably a bit premature given the reported localized
flooding/standing water issues south of the M-55 corridor.
Temperatures down that way will fall to at or below freezing this
morning which may help alleviate flooding issues. But for
now...plan to extend the flood warning out at least through the
day and allow day shift to gather reports from down that way.
&&
.SHORT TERM...(Thursday through Friday)
Issued at 332 AM EST Wed Feb 21 2018
...Dry Thursday, Mixed Precipitation Friday...
High Impact Weather Potential...Mixed precipitation again will
produce some icing and light snow amounts.
Pattern Synopsis/Forecast...The core of the sfc high is over the
Upper Great Lakes at 12z/Thu and slowly moves off to the east
through the day. At 00z/Fri, the high continues move east, and keeps
the weather clear through 06z/Fri. It isn`t until after 06z, that
the next system begins to move into the region. It looks like the
main precipitation doesn`t move into the forecast area until after
09z/Fri, and it should start as all snow. However the warm air
aloft, looking at the 850 mb temperatures there should be a decent
warm nose aloft ahead of the sfc warm air. The NAM shows that the
sfc wind will still be originating out of a relative cold air mass
to the SE of the forecast area, so it looks like Freezing rain could
be the main threat in the locations in the eastern half of the
forecast area. Models, at least through 18z keep the warm air aloft
in the eastern half of the forecast area, although the ECMWF begins
to pull the cold air in the northwest at 850 mb down over the region
during the early evening, changing things to snow, just as the event
is ending with the dry air in the 700-500 mb layer quickly drying to
<20% by 00z/Sat. This dries things out overnight.
Primary Forecast concerns...Again the P-type will be the challenge
as we get another battle for freezing/frozen precipitation with the
warm air aloft. This looks to be a quick event, which will probably
save us from having a prolonged ice event. Nevertheless, it still
looks good for an advisory level event with many locations east of
I-75 receiving 0.05 to 0.10" of ice through the morning hours at the
least.
.LONG TERM...(Friday night through Tuesday)
Issued at 332 AM EST Wed Feb 21 2018
...Above normal temperatures into Early Next Week...
Extended (Saturday through Tuesday)...It`s good news, bad news time.
first the good news. Temperatures through days 4-7 will remain above
normal as the 500 mb jet looks to venture a little more to the
north. With that being said, the bad news is that Saturday/Sunday,
will feature another mixed precipitation event. The sfc low on the
GFS remains fairly deep, while the ECMWF is still remaining a bit
weaker. As was said yesterday, the GFS being stronger looks to pull
more warm air into the region so that rain/Freezing rain could be an
issue again, while the weaker ECMWF would have some mixed
precipitation, but there is a better chance that the issue would be
freezing rain/snow. Once the system is out of the region, there is a
couple of weaker, trailing systems move through Sunday/Monday and
then Tuesday/Wednesday although timing on the specifics will be low
confidence, especially after Saturday.
&&
.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 621 AM EST Wed Feb 21 2018
High pressure and colder/drier air will overspread the region
today. Current MVFR-IFR conditions out there this morning will
give way to VFR conditions at all terminal sites as we go through
the day...and persist through tonight.
Some gustier NW winds anticipated today. But winds will diminish
quickly for tonight.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
&&
$$
NEAR TERM...BA
SHORT TERM...JL
LONG TERM...JL
AVIATION...BA